This invention relates generally to a sealing device for sealing an air barrier membrane to a wall, particularly to a wall having projecting tie rods.
A typical two wythe cavity wall comprises a first wythe of poured concrete or concrete blocks or steel or wooden studs or so forth, and a second wythe of a facing material, such as brick, block or stone. Generally, insulation material is attached to the inner wythe but a cavity is left between the insulation and the facing material. This is to permit water leakage to drain away. Many facing materials, such as brick, are quite pourous. During a heavy summer rain moisture can readily penetrate through such a facing. This moisture though is not particularly problematic, since it simply runs down the cavity and is re-directed back outside of the wall by means of flashing or so forth.
However, air and moisture can also penetrate from the interior of the building through the inner wythe. Many modern buildings are under positive internal pressure relative to the surrounding environment because of their ventilation systems. During winter, warm moist air from the interior of the building which penetrates through the inner wythe and the insulation into the cavity between the two wythes is quickly cooled, causing moisture to condense and ultimately freeze if the outside temperature is cold enough. Such air leakage has recently become recognized as a major factor in determining building performance or serviceability. It results in excessive efflorescence, spalling, and displacement of facing material.
Accordingly, it has recently been proposed that buildings of this type of construction have a completely sealed air barrier to prevent any leakage of air from the interior of the building through the inner wythe into the cavity between the insulation and the outer wythe of facing material. In fact, some jurisdictions have adopted regulations requiring the installation of such barriers. At present, two basic types of air barriers are in use. First there are sheet membranes, which generally comprise a layer of bitumen or similar material on a sheet reinforcement, for example polyethylene sheet. These may be adhered to the outer surface of the concrete wythe with an appropriate adhesive or in some cases they are heat fused to the concrete. Second, there are semi-liquid applied membranes, which essentially comprise viscous bitumen or similar material which may be trowelled onto the surface of the concrete, or sometimes sprayed.
In two wythe construction, the facing wythe is secured to the inner wythe generally by means of masonry ties. Masonry ties come in a variety of forms. Essentially, they comprise an anchor which projects outwardly from the inner wythe and which can be secured to the outer wythe, and means for securing the anchor to the inner wythe. A common type of brick tie, for example, used with inner wythes of concrete block, comprises an elongate frame with rods extending outwardly therefrom, usually in loops, on one side at regular intervals. These ties are placed within the mortar between courses of blocks, typically between every second course, with the tie rods extending outwardly to be fitted within the mortar between corresponding courses of bricks.
With the known air barrier membranes, either the sheet membrane or the liquid applied membrane, considerable time and effort must be spent to try to obtain a good seal around the masonry tie anchors which extend outwardly from the inner wythe. Anchors such as the rods of the common brick tie described above are typically positioned every 16 inches and they thus represent a considerable obstacle. Failure to obtain a complete seal of the air barrier membrane around the tie anchors, even just some of them, severely limits the effectiveness of the air barrier.
It is an object of the present invention to obviate or mitigate this and other disadvantages.